JP6746751B2 - Image analysis device, image analysis method, and program - Google Patents

Description

Embodiments of the present invention relate to an image analysis device, an image analysis method, and a program.

There is known a technique of estimating a three-dimensional positional relationship of bones from a two-dimensional image of a joint portion taken by a plain X-ray prior to a surgical operation such as osteoarthritis that occurs in a knee joint or a hip joint.

For example, Patent Document 1 discloses that an evaluation function including relative compatibility between a patient skeleton and an implant part is generated based on a CT image or an MR image. Patent Document 1 discloses that the evaluation function is used for selecting an implant suitable for a patient and for surgical planning.

Here, the bones of an actual human body are subjected to muscle tension generated by the muscles associated with the bones, and the stress acting on the joint changes due to the muscle tension. However, conventionally, the stress that takes into consideration the force exerted by the muscle has not been estimated, and the stress that actually acts on the joint part of the patient cannot be calculated with high accuracy.

JP, 2006-263241, A

The problem to be solved by the present invention is to provide an image analysis device, an image analysis method, and a program capable of calculating the stress acting on a joint with high accuracy.

According to the embodiment, the image analysis device includes a first acquisition unit, a construction unit, a first calculation unit, a second calculation unit, and a third calculation unit. The first acquisition unit acquires a CT image of a joint part of the subject and a bone part continuous with the joint part. The construction unit constructs a three-dimensional shape of the bone part and the joint part and a relationship characteristic between load and deformation in the bone part and the joint part from the CT image. The first calculator calculates a positional relationship between the bone parts continuous to the joint part. The second calculator calculates the acting force exerted by the muscle on the bone part continuous with the joint part from the positional relationship. The third calculator calculates the first stress acting on the joint based on the first dynamic model indicating the three-dimensional shape and the relationship characteristic and the acting force.

The block diagram of an image analysis apparatus. The schematic diagram of a 1st dynamic model. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The flowchart which shows the procedure of an image analysis process. The block diagram of an image analysis apparatus. The schematic diagram of an artificial joint model. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The schematic diagram of an analysis image. The flowchart which shows the procedure of an image analysis process. The block diagram of an image analysis apparatus. The schematic diagram of an external device. The flowchart which shows the procedure of an image analysis process. The hardware block diagram of an image analysis apparatus.

(First embodiment)
Hereinafter, an image analysis device, an image analysis method, and a program according to embodiments will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of an image analysis device 10 according to the present embodiment. The image analysis device 10 of the present embodiment is a device that analyzes a joint of a subject.

The image analysis device 10 is connected to the external device 18. The external device 18 is a device that acquires image information to be analyzed by the image analysis device 10. The image information to be analyzed is image information about the joint part of the subject and the bone part continuous to the joint part. Specifically, the image information to be analyzed includes the joint of the subject, the bone that is continuous with the joint, and the muscle. The muscle portion includes a muscle.

The external device 18 obtains time-series CT image information of the subject and time-series MR image information of the subject by scanning the subject with X-rays or magnetism, for example. The image analysis device 10 may include the external device 18.

Hereinafter, a case where the image information to be analyzed handled in this embodiment is CT image information will be described. However, the image information to be analyzed is not limited to CT image information. For example, the image information to be analyzed may be MR image information or ultrasonic echo image information.

The CT image information may be slice data expressing a two-dimensional spatial distribution of CT values or volume data expressing a three-dimensional spatial distribution of CT values. Hereinafter, the CT image information is assumed to be volume data. The external device 18 outputs the time-series CT image information to the image analysis device 10. Further, the image analysis device 10 may acquire the CT image information to be analyzed from another device or a storage unit that stores time-series CT images. The image information to be analyzed by the image analysis device 10 is not limited to time-series images. In the following description, the image information to be analyzed will be simply referred to as an image or a CT image.

The image analysis device 10 includes a control unit 12, a UI unit 14, and a storage unit 16. The UI unit 14 and the storage unit 16 are connected to the control unit 12 so that data and signals can be exchanged. The controller 12 is also connected to the external device 18.

The UI unit 14 includes an input unit 14A and a display unit 14B. The input unit 14A receives various instructions and information inputs from the user. The input unit 14A is, for example, a keyboard, a mouse, a switch, a microphone, or the like.

The display unit 14B displays various information such as CT images and analysis results. The display unit 14B is, for example, a CRT display, a liquid crystal display, an organic EL display, a plasma display, or the like.

The UI unit 14 may have a touch panel function in which the input unit 14A and the display unit 14B are integrally configured.

The storage unit 16 is composed of various storage media such as a hard disk device. The storage unit 16 stores various data such as time-series CT images. For example, the storage unit 16 stores the time-series CT images in a medical image file format that complies with DICOM (digital imaging and communications in medicine) standards. The storage unit 16 may store the medical data collected by the control unit 12 or the like in association with the time-series CT images.

The control unit 12 controls the image analysis device 10. The control unit 12 includes a first acquisition unit 12A, a first calculation unit 12B, a second calculation unit 12C, a reception unit 12D, a construction unit 12E, a third calculation unit 12F, a generation unit 12G, and a display control. And a portion 12H. Part or all of the first acquisition unit 12A, the first calculation unit 12B, the second calculation unit 12C, the reception unit 12D, the construction unit 12E, the third calculation unit 12F, the generation unit 12G, and the display control unit 12H are, for example, A processor such as a CPU (Central Processing Unit) may execute the program, that is, it may be realized by software, or may be realized by hardware such as an IC (Integrated Circuit), or software and hardware. You may implement together.

The first acquisition unit 12A acquires an image of a joint part of a subject and a bone part continuous to the joint part. In the present embodiment, the first acquisition unit 12A acquires an CT image from the external device 18 to obtain an image (hereinafter referred to as a CT image) of the joint part of the subject and a bone part continuous to the joint part. get. The CT image of the subject may be stored in the storage unit 16 in advance. In this case, the first acquisition unit 12A may acquire the CT image by reading the CT image of the subject to be analyzed from the storage unit 16.

The first acquisition unit 12A outputs the acquired CT image to the first calculation unit 12B and the construction unit 12E.

The constructing unit 12E constructs the three-dimensional shape of the bone and joint and the relational characteristics of the load and deformation of each bone and joint from the CT image acquired by the first acquiring unit 12A.

In the present embodiment, the case where the construction unit 12E constructs a first dynamic model that shows at least the three-dimensional shapes of bones and joints and the relational characteristics between load and deformation will be described as an example. The first mechanical model is data in which relational characteristics between the load and the deformation of each of the bone and joint are added to the bone-joint shape model showing the three-dimensional shapes of the bone and joint. The relationship characteristic between load and deformation indicates the relationship of deformation with respect to load. The relationship characteristic between load and deformation indicates hardness, for example.

In the following, in order to simplify the description, the relationship characteristic between the load and the deformation may be simply referred to as “hardness”. However, the "hardness" referred to in the present embodiment is an example of the relationship characteristic between load and deformation as described above, and the relationship characteristic is not limited to hardness.

Specifically, the construction unit 12E extracts the bone region from the CT image acquired by the first acquisition unit 12A. For example, when the image to be analyzed is a CT image, the CT value of hard bone is about 1000 HU, and the CT value of soft tissue that is connective tissue excluding bone such as tendon, ligament, and muscle is about 0 to 100 HU. Therefore, the constructing unit 12E presets the threshold value of the CT value for distinguishing between the bone part and the soft tissue. The threshold may be adjustable by the user operating the input unit 14A or the like.

Then, the construction unit 12E extracts the joint region and the bone region from the CT image acquired by the first acquisition unit 12A by extracting the region having the CT value equal to or more than the threshold value, and the tertiary region of the joint and the bone region is extracted. A bone joint shape model showing the original shape is generated.

For example, in the image analysis device 10, when the structural analysis of the joint part is performed by the numerical analysis using the finite element method (FEM: Finite Element Method), the construction part 12E defines the three-dimensional finite element model as the joint part It is generated as a bone joint shape model of the bone part. The finite element method is a method of dividing a region to be analyzed into mesh-shaped regions (called elements) surrounded by nodes and approximating the deformation.

Further, the building unit 12E generates a first mechanical model in which the relational characteristics between the load and the deformation of each of the bone part and the joint part are added to the bone joint shape model. Here, the CT value differs depending on the physical properties. Therefore, the constructing unit 12E calculates, for each element, the relationship characteristic between the load and the deformation, such as the hardness of the bone portion and the joint portion, according to the CT value, and each element at the corresponding position of the bone joint shape model. To generate a first dynamic model. Further, the obtained shape model may be filtered so as to remove discontinuous portions.

Here, the displacement includes displacement due to rigid body displacement and displacement due to material deformation of each part. Therefore, the construction unit 12E may separate the displacement due to the rigid body displacement from the displacement due to the material deformation of each part, and calculate the relational characteristics between each load and the deformation for each element.

Specifically, the constructing unit 12E is a living tissue other than the bone portion and the joint portion, and is not likely to be deformed due to factors other than the load, and the deformation due to the load can be extracted, The second relationship characteristic of may be further constructed. The factors other than the load are specifically factors other than the load, such as the degree of hyperemia of blood in the muscle fibers and the sliding movement of the filaments forming the muscle fibers. Such living tissues are, for example, tendons, ligaments, and cartilage.

In this case, the constructing unit 12E uses the image analysis and tracking technology to analyze the deformation amount of the tendon, ligament, and cartilage that are continuous or associated with the bone or joint included in the CT image, and the relationship characteristics between the load and the deformation. It suffices to calculate (the second relation characteristic) for each element. Then, the constructing unit 12E adds the relationship characteristic of each of the bone portion and the joint portion and the second relationship characteristic of the biological tissue such as the tendon, the ligament, and the cartilage to each element at the corresponding position of the bone joint shape model. By doing so, the first dynamic model may be constructed.

FIG. 2 is a diagram schematically showing an example of the first dynamic model 20. The first mechanical model 20 includes a bone joint shape model showing the three-dimensional shape of each of the joint portion 24 and the bone portions 22A and 22B as the bone portions 22 continuous to the joint portion 24. 24 is data to which relational characteristics between load and deformation of the bone 24 and the bone portion 22 are added.

Returning to FIG. 1, in the present embodiment, the construction unit 12E calculates the relational characteristics between the load and the deformation, such as the hardness of the bones and joints, according to the CT value, and the correspondence of the bone joint shape model is calculated. The first dynamic model is generated by adding each element at the position to be turned.

Here, an example of a method of calculating the relationship characteristic between the load and the deformation for each element calculated by the construction unit 12E will be described.

The constructing unit 12E targets the bones and joints (which may include biological tissues such as tendons, ligaments, and cartilage described above) and applies load conditions to the tendons and the epiphyses. The construction unit 12E also applies displacement boundary conditions to the bone ends (the ends of the bones) and the joints. The construction unit 12E also gives a material constitutive equation to each living tissue. Then, the constructing unit 12E performs large deformation/stress analysis based on continuum mechanics (reference document: “First Course in Continuum Mechanics (3rd Edition)”, YC Fung).

Large deformation/stress analysis means, for example, discretizing the equations of continuum mechanics by the finite element method and then obtaining numerical values for physical quantities such as stress, strain, pressure, and deformation, and their temporal changes. Show. The large deformation/stress analysis is not limited to the elastic analysis of isotropic deformation, but may also be an analysis by a homogenization method that considers anisotropic deformation characteristics of bones. Non-linear analysis considering characteristics, static analysis or dynamic analysis may be used.

Then, the constructing unit 12E calculates the relation characteristic between the load and the deformation of each element in the bone and joint by the large deformation/stress analysis from the CT image acquired by the first acquiring unit 12A. The construction unit 12E is a living tissue other than the bone portion and the joint portion, and is not likely to be deformed by factors other than the load, and the deformation due to the load can be extracted (tendon, cartilage, ligament, etc.) The second relationship characteristic between load and deformation is further constructed (calculated) by image analysis and tracking technology. Then, the constructing unit 12E generates the first dynamic model by adding the calculated relational characteristic and the second relational characteristic to each element at the corresponding position in the bone joint shape model.

The constructing unit 12E may construct the first dynamic model in which the relational characteristic is added to each element at the corresponding position in the bone joint shape model (that is, the second relational characteristic is not included). However, it is preferable to construct the first dynamic model including the second relation characteristic from the viewpoint of improving the calculation accuracy of the first stress described later.

Returning to FIG. 1, the first calculation unit 12B calculates the positional relationship between the bone parts continuous to the joint part using the CT image received from the first acquisition unit 12A.

The positional relationship between the bone parts continuous to the joint part includes the angle (joint angle) about the joint part between the bone parts continuous to the joint part, the central coordinate system of the bone part, the moment of inertia, the mass of the bone part, the muscle. Including Jacobian, etc.

In the present embodiment, the first calculation unit 12B calculates the positional relationship using the CT image received from the first acquisition unit 12A, and generates the musculoskeletal model.

The musculoskeletal model is a bone-joint shape model showing the three-dimensional shapes of the joint and the bone, and the three-dimensional shape of the muscle is arranged and the above-mentioned positional relationship is given. The musculoskeletal model may be a model in which three-dimensional shapes of ligaments and tendons are further arranged. The muscle portion in the present embodiment means a muscle in which one of the two bone portions continuous to the joint portion is connected as a start portion and the other as a stop portion.

Therefore, the musculoskeletal model at least shows the positional relationship between the joint portion and the bone portion continuous with the joint portion. The musculoskeletal model may further include the hardness and weight of each of the bone portion, the joint portion, and the muscle portion connected to the bone portion.

For example, the first calculating unit 12B generates a musculoskeletal model from the CT image using the following method.

Specifically, the first calculating unit 12B extracts a region having a CT value equal to or more than a threshold value from the CT image acquired by the first acquiring unit 12A in the same manner as the construction unit 12E, and thereby the joint region and the bone The partial region is extracted, and a bone joint shape model showing the three-dimensional shape of the joint portion and the bone portion is generated. Further, the first calculation unit 12B extracts the region of the CT value indicating the soft tissue (muscle part) from the CT image to extract the muscle part region and arranges the three-dimensional shape of the muscle part in the bone joint shape model. To do.

Then, the first calculating unit 12B further determines, from the CT image, the joint angle, the central coordinate system of the bone part, the moment of inertia, the mass of the bone part, as the positional relationship between the joint part and the bone part continuous to the joint part. Calculate the muscle Jacobian.

For example, the first calculating unit 12B extracts, from the generated bone joint shape model, several points having characteristic shapes for each of the bone portion and the joint portion. Then, the first calculating unit 12B calculates a coordinate system centered on those barycentric positions as the central coordinate system of each bone and joint.

The first calculator 12B calculates the moment of inertia I for each of the bones and joints around the respective axes of the calculated central coordinate system using the following formula (1).

I=Σmir ² ... Formula (1)

In the equation (27), I represents the moment of inertia, mi represents the mass of the element when the bone part and the joint part are subdivided into a mesh, and ri represents the distance to the coordinate axis. The mass of the element may be calculated from the standard density and the volume of the element stored in advance. Further, ri may be calculated from the bone joint shape model.

Further, the first calculator 12B calculates the joint angle by performing coordinate conversion on the coordinate system of two adjacent bones that are continuous with the joint. For example, if the trunk near the side of the bone coordinate system (homogeneous transformation matrix) and T _a, the homogeneous transformation matrix representing the coordinate system of the distal bone and T _b, the relationship of the following formula (2) It holds. These coordinate systems may be calculated from the bone joint shape model.

^T ₌ T _b T ^{a -1} ··· formula (2)

The first calculating unit 12B compares the matrix when rotated by α, β, γ around the x-axis, the y-axis, and the z-axis, respectively, and T with the formula (2), The angles α, β, γ are calculated (Euler angle definition).

Further, the first calculator 12B calculates the muscle Jacobian using the following formula (3).

L=dl/dθ Equation (3)

In the formula (3), L represents the muscle Jacobian, dl represents the minute change amount of the muscle length, and dθ represents the minute change of the joint angle. A predetermined value may be used for dl and dθ, or may be calculated from the geometrical relationship between the muscle extracted from the CT image and the joint center.

The inertial moment, the masses of the bones and joints, and the muscle Jacobian may be calculated in advance by the control unit 12 as standard values and stored in the storage unit 16 in advance as standard positional relationships. Then, the first calculator 12B may use the moment of inertia, the masses of the bones and joints, and the muscle Jacobian stored in the storage 16. In addition, when the first calculation unit 12B newly calculates at least one of the moment of inertia, the mass of the bone part, the mass of the joint part, and the muscle Jacobian, the calculated value is set as a new value, and the storage unit The storage unit 16 may be updated by storing the data in the storage unit 16.

Then, the first calculating unit 12B arranges the three-dimensional shape of the muscle portion in the bone joint shape model showing the three-dimensional shapes of the joint portion and the bone portion, and calculates the positional relationship (joint angle, central coordinate system of the bone portion). , Moment of inertia, mass of bones and joints, muscle Jacobian, etc.) to generate a musculoskeletal model.

The first calculating unit 12B generates the musculoskeletal model from each of the time-series CT images, so that the first calculating unit 12B generates the time-series musculoskeletal model. That is, the first calculating unit 12B generates a time-series musculoskeletal model to change the joint angle or the muscle length from the time change of the position of the bone part extracted from the CT images acquired in time series. Changes can also be calculated.

The second calculating unit 12C calculates the acting force exerted by the muscle on the bone portion continuous with the joint portion, from the positional relationship calculated by the first calculating unit 12B.

The acting force includes, for example, at least one of a muscle tension of a muscle coupled between bone parts continuous to the joint part and a torque acting on the joint part. The muscle connected between the bone parts continuous to the joint part means that one bone part of the two bone parts continuous to the joint part is the starting part and the other bone part is the stop part and is connected to these bone parts. Shows the streaked muscle.

Specifically, the second calculator 12C calculates the acting force acting on the joint by the muscle by performing inverse dynamics calculation based on the positional relationship calculated by the first calculator 12B.

The inverse dynamics calculation requires the joint angle, the central coordinate system of the bone part, the moment of inertia, the mass of the bone part, and the muscle Jacobian as the positional relationship between the joint part and the bone part continuous to the joint part. The second calculator 12C acquires the joint angle, the central coordinate system of the bone part, the moment of inertia, the mass of the bone part, and the muscle Jacobian from the musculoskeletal model calculated by the first calculator 12B.

Then, the second calculator 12C uses the joint angle, the central coordinate system of the bone part, the moment of inertia, the mass of the bone part, and the muscle Jacobian to calculate the inverse dynamics by the following formulas (4) to (6). By performing, the acting force acting by the muscle on the joint is calculated. The following formula (4) is a formula for calculating the torque acting on the joint.

The equation of motion at each joint is expressed by equation (4).

τ=Md ² θ/dt ² +Dd θ/dt+G(θ) (4)

In the equation (4), τ represents the torque acting on the joint, θ represents the joint angle, and dθ/dt represents the joint angular velocity. Further, d ² θ/dt ² indicates the joint angular acceleration, M indicates the moment of inertia, D indicates the viscous resistance, and G(θ) indicates the gravitational term (change depending on the posture).

The second calculating unit 12C obtains the joint angular velocity (dθ/dt) by calculating the angular velocity of the joint angle using the time-series musculoskeletal model calculated by the first calculating unit 12B. Good. The second calculator 12C calculates the angular velocity of the joint angle using the time-series musculoskeletal model calculated by the first calculator 12B for the joint angular acceleration (d ² θ/dt ² ). Can be obtained by The viscous resistance (D) may be measured in advance and stored in the storage unit 16. The gravity term (G(θ)) may be calculated from the mass of the bone part and the position of the center of gravity.

In addition, when the CT image acquired by the first acquisition unit 12A is not a time-series image (that is, a one-shot CT image), it is not possible to obtain the item regarding the time change in Expression (4). Therefore, in this case, the second calculator 12C may proceed with the process with τ=G(θ).

In addition, the second calculator 12C calculates the muscle tension of the muscle connected between the bones continuous to the joint by performing the inverse dynamics calculation.

Here, when the additional load F is acting on the joint, the following formula (5) is established according to the principle of virtual work.

J ^T F+τ=L ^T m (Equation (5))
m=(L ^T ) ⁻¹ (J ^T F+τ) Equation (6)

In Expressions (5) and (6), J represents the joint angle Jacobian (the differential relationship between the position and the joint angle), L represents the muscle Jacobian (the differential relationship between the joint angle and the muscle length), and m represents Indicates muscle tension. In the above formula (5), the second calculator 12C calculates the muscle tension m by multiplying the left side by the inverse matrix of L ^T (see formula (6)).

The second calculator 12C may obtain the joint angle Jacobian (J) in the equations (6) and (6) by partially differentiating the additional load (vector) by the joint angle (vector). ..

Through the above processing, the second calculation unit 12C performs the inverse dynamics calculation based on the positional relationship (musculoskeletal model) calculated by the first calculation unit 12B, and thereby the acting force exerted by the muscle on the joint ( Calculate the muscle tension and the torque that acts on the joint.

Note that the second calculator 12C may calculate the acting force by assuming a viscoelastic model that simulates a more actual muscle as the physical model of the muscle.

Next, the third calculator 12F will be described.

The third calculation unit 12F calculates the first stress acting on the joint based on the three-dimensional shape constructed by the construction unit 12E, the relationship characteristic, and the acting force calculated by the second calculation unit 12C. .. In the present embodiment, the third calculation unit 12F calculates the first stress acting on the joint based on the first dynamic model constructed by the construction unit 12E and the acting force calculated by the second calculation unit 12C. A case of calculating will be described. That is, the third calculator 12F calculates the first stress for each element (each element in the FEM) on the contact surface between the bone portion and the joint portion.

Specifically, the third calculating unit 12F gives the muscle tension and the torque acting on the joint, which are calculated by the inverse dynamics calculation by the second calculating unit 12C, as the boundary condition of the external load for the first dynamic model. .. Accordingly, the third calculator 12F structurally analyzes the joint, and calculates the first stress that acts on the cartilage, which is the contact surface between the bone and the joint. Numerical analysis using a known finite element method (FEM) may be used to calculate the first stress.

The third calculator 12F calculates the first stress of each element on the contact surface between the bone and the joint, thereby acting on the joint (that is, the contact surface between the bone and the joint). 1 Calculate the stress distribution.

The generation unit 12G generates an analysis image including a first stress image that indicates the first stress acting on the joint calculated by the third calculation unit 12F. The first stress image is a stress image in which a stress region in which the first stress acts on the contact surface between the bone part and the joint part of the subject is shown with a color density corresponding to the intensity of the first stress. In this embodiment, the color density indicates at least one of color and density.

In the present embodiment, the generation unit 12G determines, in the bone part image showing the three-dimensional shape of the bone part, the stress region in which the first stress acts on the contact surface between the bone part and the joint part as the strength of the first stress. A stress image represented by a color density corresponding to is generated as the first stress image.

The reception unit 12D receives various operation instructions from the user from the input unit 14A.

The display control unit 12H controls the display unit 14B to display the analysis image 34 including the first stress image 30 generated by the generation unit 12G (see FIGS. 3 to 6).

FIG. 3 is a diagram showing an example of the analysis image 34. For example, the analysis image 34 includes the first dynamic model image 32 and the first stress image 30. The analysis image 34 may be an image including at least the first stress image 30. When the analysis image 34 includes the first dynamic model image 32, the generation unit 12G may generate the first dynamic model image 32 and generate the analysis image 34 including the first dynamic model image 32 and the first stress image 30. ..

The first stress image 30 shows the bone part image 40 and the stress region 42 in which the first stress acts on the contact surface between the bone part and the joint part, with the color density according to the strength of the first stress acting. It is a stress image. In the example shown in FIG. 3, the stress region 42 is indicated by the color density indicating that the first stress is “0”.

The first stress image 30 may further include a gauge 36 that indicates the color density corresponding to the strength of the first stress.

The gauge 36 displays, for example, a list of color densities corresponding to the intensity of the first stress and the values of the first stress corresponding to each color density in association with each other. That is, in the example shown in FIG. 3, the stress region 42 is indicated by the color density (36 ₁₄ ) indicated by the gauge 36 and indicating that the first stress is “0”. Therefore, the user can easily confirm that the first stress of the value “0” is acting on the stress region 42 by visually recognizing the first stress image 30.

The analysis image 34 may further include the first dynamic model image 32 showing the first dynamic model. The first dynamic model image 32 includes a shape model image 44 and a gauge 38.

In the shape model image 44, the distribution and strength of the first stress acting on the contact surface between the bone portion and the joint portion are the same as those of the first stress image 30 included in the same analysis image 34. 3 is an image showing a three-dimensional shape of the positional relationship between the bone part and the joint part in the case of the height.

The gauge 38 is an image in which a list of color densities corresponding to the strength of the relationship characteristics between load and deformation and the values of the relationship characteristics corresponding to each color density are displayed in association with each other. The shape model image 44 is provided with a color density according to the value of the relationship characteristic between load and deformation.

By the generation unit 12G generating the analysis image 34 including the first stress image 30, the display unit 14B displays the analysis image 34 illustrated in FIG. 3, for example. Therefore, the image analysis device 10 displays the first stress image 30 in which the stress region 42 in which the first stress acts on the contact surface between the bone part and the joint part is shown with the color density corresponding to the intensity of the first stress. Can be displayed. Therefore, the image analysis device 10 can easily provide the user with the position and range on the contact surface between the bone portion and the joint portion where the first stress of each strength acts.

In addition, the generation unit 12G generates the analysis image 34 including the first stress image 30 and the first dynamic model image 32, so that the display unit 14B displays the analysis image 34 illustrated in FIG. 3, for example. To be done. Therefore, the image analysis device 10 can easily provide the positional relationship between the joint portion 24 and the bone portion 22 when the first stress indicated by the first stress image 30 is acting.

Here, the generation unit 12G may change the positional relationship between the joint portion 24 and the bone portion 22 and generate the first stress image 30 and the first dynamic model image 32 according to the change in the positional relationship.

For example, the generation unit 12G determines that the positional relationship between the joint portion 24 and the bone portion 22 is from 180° to the angle (joint angle) formed by the two bone portions 22 continuous with the joint portion 24 with the joint portion 24 as the center. The first calculator 12B, the constructing unit 12E, the second calculator 12C, and the third calculator 12F are controlled so as to calculate the first stress acting on the joint 24 when the angle is changed between 45°. To do. Then, the generation unit 12G acquires the distribution of the first stress according to the joint angle from the third calculation unit 12F.

It is assumed that the time-series CT images acquired by the first acquisition unit 12A are images in which the joint angle is changed (for example, changed between 180° and 45°). In this case, using each of the time-series CT images acquired by the first acquisition unit 12A, the first calculation unit 12B, the second calculation unit 12C, the construction unit 12E, and the third calculation unit 12F perform the above processing, The distribution of the first stress according to each joint angle is calculated. Therefore, in this case, the generation unit 12G may acquire the distribution of the first stress according to the joint angle from the third calculation unit 12F.

Then, the generation unit 12G generates the first stress image 30 corresponding to each joint angle. The display control unit 12H displays the analysis image 34 including the first stress image 30 generated by the generation unit 12G on the display unit 14B. At this time, the generation unit 12G may generate the first dynamic model image 32 and generate the analysis image 34 including the first stress image 30 and the first dynamic model image 32.

In this case, the display control unit 12H displays the analysis image 34 on the display unit 14B, so that, for example, the analysis image 34 illustrated in FIGS. 3, 4, and 5 is displayed on the display unit 14B.

FIG. 3 shows a first dynamic model image 32A and a first stress image 30A when an angle (joint angle) formed by two bone parts 22A and 22B continuous to the joint part 24 is about 180°. It is a figure which shows an example of the analysis image 34A containing. In the example shown in FIG. 3, the stress region 42 is indicated by the color density (36 ₁₄ ) which is indicated by the gauge 36 and indicates that the first stress is “0”.

FIG. 4 shows a first dynamic model image 32B and a first stress image 30B when an angle (joint angle) formed by two bone portions 22A and 22B continuous to the joint portion 24 is about 120°. It is a figure which shows an example of the analysis image 34B containing. In the example shown in FIG. 4, the stress region 42 ₁ in the contact surface between the bone portion and the joint portion is indicated by the color density 36 ₁ indicating the first stress “8×10 ⁻¹ ”. Further, the stress area 42 _5, are indicated by color density 36 ₅ showing a first stress "5.333 × ^{10 -1".} Further, the stress region 42 ₈ is indicated by the color density 36 ₈ showing a first stress "4.0 × ^{10 -1",} the outermost stress regions _{42 14,} color density shows a first stress "0" 36 It is shown at ₁₄ .

Further, in FIG. 4, the first mechanical model image 32B included in the analysis image 34B is an image showing that the angle between the bone portion 22A and the bone portion 22B is approximately 120°.

FIG. 5 shows a first dynamic model image 32C and a first stress image 30C when an angle (joint angle) formed by two bone portions 22A and 22B continuous to the joint portion 24 is about 90°. It is a figure which shows an example of 34 C of analysis images containing. Similar to FIG. 4, in the example shown in FIG. 5, each stress region 42 is represented by a color density corresponding to the strength of the first stress acting. In the stress region 42 shown in FIG. 5, the range of the region where the first stress is strong is larger than the color density of the stress region 42 shown in FIG.

Thus, the generation unit 12G causes the first stress image 30 (first stress images 30A, 30B, 30C) and the first dynamic model image 32 (according to the change in the positional relationship between the joint portion 24 and the bone portion 22) to be generated. First dynamic model images 32A, 32B, 32C) are generated. Then, the display control unit 12H causes the first stress image 30 (first stress images 30A, 30B, 30C) and the first dynamic model image 32 (first dynamic model images 32A, 32B) corresponding to changes in these positional relationships. , 32C) are displayed on the display unit 14B.

Therefore, the image analysis device 10 determines the strength of the first stress and the position where the first stress acts on the contact surface between the bone part and the joint part according to the change in the positional relationship between the joint part 24 and the bone part 22. The range and the range can be easily provided to the user.

In addition, when the joint angle is input by the operation of the input unit 14A by the user, the generation unit 12G may generate the first stress image 30 and the first dynamic model image 32 according to the input joint angle. Good. Then, the display control unit 12H may display the analysis image 34 including the first stress image 30 and the first dynamic model image 32 generated according to the input joint angle on the display unit 14B. In addition, when the user operates the input unit 14A to instruct to display the analysis image in which the positional relationship is changed, the display control unit 12H causes the first stress image 30 and the first dynamics corresponding to the generated joint angle. The model images 32 may be sequentially displayed in the display unit 14B in order of increasing or decreasing joint angles.

The display control unit 12H may display the first stress image 30 on the display unit 14B, the first stress image 30 selectively including the stress region 42 of the first stress of the strength designated by the user.

In this case, for example, when the display control unit 12H is displaying the analysis image 34 on the display unit 14B, the first stress having a predetermined strength indicated by the gauge 36 is instructed by an operation instruction of the input unit 14A by the user. Suppose The reception unit 12D receives a signal indicating the intensity of the first stress instructed by the user from the input unit 14A.

When the display control unit 12H receives the signal indicating the intensity of the first stress from the reception unit 12D while displaying the analysis image 34 including the first stress image 30 on the display unit 14B, the display control unit 12H displays the first stress image. Of the stress regions 42 in the 1-stress image 30, the first stress image 30 selectively showing only the stress regions 42 on which the first stress of the designated strength acts is displayed on the display unit 14B.

In this case, for example, when the first stress image 30C shown in FIG. 5 is displayed on the display unit 14B, the first stress “8×10 ⁻¹ ” in the gauge 36 is given by the operation instruction of the input unit 14A by the user. the display area of the color density 36 ₁ shown is instructed. In this case, the display control unit 12H is at the interface between the bone and the joint, the stress area 42 ₁ which acts in the intensity of the first stress corresponding to the color density 36 ₁ "8 × 10 ^-1", selected The first stress image 30D shown schematically may be displayed on the display unit 14B (see FIG. 6).

The display control unit 12H may emphasize the stress region 42 of the first stress having the strength designated by the user, as compared with the other regions.

Further, the display control unit 12H may display the first stress image 30 on the display unit 14B, which selectively includes the stress region 42 of the first stress in the strength range designated by the user. In this case, the display control unit 12H may display, on the display unit 14B, the first stress image 30 that selectively shows the stress region 42 in which the first stress acts in the strength range designated by the user.

Next, the procedure of the image analysis process executed by the image analysis apparatus 10 will be described. FIG. 7 is a flowchart showing an example of the procedure of the image analysis processing executed by the image analysis apparatus 10.

First, the receiving unit 12D determines whether the analysis instruction is received from the input unit 14A (step S100). For example, the user operates the input unit 14A to instruct image analysis or display of an analysis image. When receiving the signal indicating the image analysis from the input unit 14A, the reception unit 12D determines that the analysis instruction has been received (step S100: Yes).

When a positive determination is made in step S100 (step S100: Yes), the first acquisition unit 12A acquires a CT image (step S102).

Next, the construction unit 12E constructs a first dynamic model from the CT image acquired in step S102 (step S104).

Next, the 1st calculation part 12B calculates the positional relationship of the bone part which follows a joint part using the CT image acquired by step S102 (step S106).

Next, the second calculating unit 12C calculates the acting force exerted by the muscle on the bone part continuous to the joint part from the positional relationship calculated by the first calculating unit 12B (step S108).

Next, the third calculating unit 12F acts on the joint based on the first dynamic model constructed by the constructing unit 12E in step S104 and the acting force computed by the second calculating unit 12C in step S108. One stress is calculated (step S110).

Next, the generation unit 12G generates a first stress image showing the first stress calculated in step S110 (step S112). In the present embodiment, as described above, the generation unit 12G generates the analysis image including the first stress image.

Next, the generation unit 12G stores the analysis image generated in step S112 in the storage unit 16 (step S114). Then, this routine ends. In step S114, the generation unit 12G preferably stores the analysis image generated in step S112 in the storage unit 16 in association with the identification information for identifying the analysis image. This identification information is, for example, at least one of the subject ID of the subject of the CT image acquired in step S102, the date and time of the CT image, the date and time of generation of the analysis image, and the joint angle of the joint included in the CT image. It is preferable to include one. In this case, for example, the first acquisition unit 12A may acquire the CT image, the object ID of the object of the CT image, and the imaging date and time of the CT image. Then, the generation unit 12G may use the subject ID and the shooting date and time as identification information. Further, the generation unit 12G may receive the joint angle of the joint portion included in the first stress image included in the analysis image from the second calculation unit 12C. Then, the generation unit 12G may use the accepted joint angle as identification information.

On the other hand, when the receiving unit 12D makes a negative determination in step S100 (step S100: No), the process proceeds to step S116. For example, when the reception unit 12D receives a signal indicating the display of the analysis image from the input unit 14A, the reception unit 12D makes a negative determination in step S100. Next, the reception unit 12D determines whether or not a display instruction has been received. For example, the reception unit 12D determines whether or not the display instruction of the analysis image is received from the input unit 14A. If an affirmative decision is made in step S116 (step S116: Yes), the operation proceeds to step S118. On the other hand, if a negative decision is made in step S116 (step S116: No), this routine is ended.

Next, the display control unit 12H reads the analysis image stored in the storage unit 16 (step S118). Then, the display control unit 12H performs control to display the read analysis image on the display unit 14B (step S120). Then, this routine ends.

In the process of step S118, the display control unit 12H reads at least one of the list of analysis images stored in the storage unit 16 and the list of identification information corresponding to the analysis images, and displays it on the display unit 14B. May be. Then, the user operates the input unit 14A to select the analysis image to be displayed or the identification information corresponding to the analysis image to be displayed. When the accepting unit 12D accepts the analysis image to be displayed or the signal indicating the identification information from the input unit 14A, the display control unit 12H analyzes the signal indicating the accepted analysis image or the signal indicating the accepted identification information. The image may be read from the storage unit 16 and displayed on the display unit 14B.

The procedure of the image analysis processing shown in FIG. 7 is an example, and the procedure of the image analysis processing executed by the image analysis apparatus 10 is not limited to the order shown in FIG. 7. For example, the processing of step S104 may be performed after the processing of steps S106 to S108. Further, the processing of step 104 and the processing of steps S106 to S108 may be performed in parallel.

As described above, the image analysis device 10 according to the present embodiment includes the first acquisition unit 12A, the construction unit 12E, the first calculation unit 12B, the second calculation unit 12C, and the third calculation unit 12F. Equipped with. The first acquisition unit 12A acquires an image of a joint part of a subject and a bone part continuous to the joint part. The constructing unit 12E constructs the three-dimensional shape of the bone and joint and the relational characteristics of the load and deformation in the bone and joint from the image. The first calculator 12B calculates the positional relationship between the bones that are continuous with the joint. The second calculator 12C calculates the acting force exerted by the muscle on the bone part continuous to the joint part from the positional relationship. The third calculator 12F calculates the first stress acting on the joint based on the three-dimensional shapes of the bone and the joint, the relational characteristics between the load and the deformation, and the acting force.

As described above, in the image analysis device 10 according to the present embodiment, the first stress acting on the joint part is calculated by using the acting force acting by the muscle on the bone part continuous to the joint part and the first dynamic model. calculate. Therefore, the image analysis device 10 according to the present embodiment can calculate the stress acting on the joint part in consideration of the force acting by the muscle.

Therefore, in the image analysis device 10 of the present embodiment, the stress acting on the joint part of the subject can be calculated with high accuracy.

(Second embodiment)
In this embodiment, a case will be described in which the second stress acting on the artificial joint is further calculated. In addition, in the present embodiment, a case of modeling an artificial joint model will be described.

FIG. 8 is a configuration diagram of the image analysis apparatus 11A of the present embodiment. The image analysis device 11A is connected to the external device 18. The external device 18 is similar to that of the first embodiment.

The image analysis device 11A includes a control unit 13, a UI unit 14, a storage unit 16, and a modeling unit 15. The UI unit 14, the storage unit 16, the modeling unit 15, and the external device 18 are connected to the control unit 13 so that data and signals can be exchanged.

The UI unit 14 and the storage unit 16 are the same as those in the first embodiment.

The modeling unit 15 is a known device that manufactures a three-dimensional model. The modeling unit 15 may be any device that can model a three-dimensional model. The modeling unit 15 may be, for example, either a hot melt laminating method or a powder fixing method.

In the present embodiment, the material used by the modeling unit 15 for modeling is preferably a material that satisfies the range of mechanical properties of human bones, joints, and cartilage.

The control unit 13 controls the image analysis device 11A. The control unit 13 includes a first acquisition unit 12A, a first calculation unit 13B, a second calculation unit 13C, a first control unit 13D, a reception unit 12D, a construction unit 12E, and a third calculation unit 12F. The second acquisition unit 13E, the fourth calculation unit 13F, the generation unit 13G, the display control unit 13H, and the modeling control unit 13I are included.

1st acquisition part 12A, 1st calculation part 13B, 2nd calculation part 13C, 1st control part 13D, acceptance part 12D, construction part 12E, 3rd calculation part 12F, 2nd acquisition part 13E, 4th calculation part 13F, Some or all of the generation unit 13G, the display control unit 13H, and the modeling control unit 13I may be realized by causing a processing device such as a CPU to execute a program, that is, by software, or by hardware such as an IC. It may be realized by hardware, or may be realized by using software and hardware together.

The first acquisition unit 12A, the reception unit 12D, the construction unit 12E, and the third calculation unit 12F are the same as those in the first embodiment. Therefore, the first acquisition unit 12A, the reception unit 12D, the construction unit 12E, and the third calculation unit 12F will be described in a simplified manner.

The first acquisition unit 12A acquires an image (in the present embodiment, a case of a CT image will be described) regarding a joint part of a subject and a bone part continuous to the joint part. The first acquisition unit 12A outputs the acquired CT image to the first calculation unit 13B and the construction unit 12E.

The construction unit 12E constructs a first dynamic model from the CT image acquired by the first acquisition unit 12A.

Similar to the first calculating unit 12B of the first embodiment, the first calculating unit 13B uses the CT image received from the first acquiring unit 12A to calculate the positional relationship between the bones that are continuous with the joint. , Generate a musculoskeletal model. As described above, the positional relationship is the angle (joint angle) about the joint between the bones continuous to the joint, the center coordinate system of the bone, the moment of inertia, the mass of the bone, the muscle Jacobian, etc. including. As described in the first embodiment, the inertial moment, the mass of the bone portion, and the muscle Jacobian may be calculated in advance by the control unit 13 as standard values and stored in the storage unit 16 in advance. .. Then, the first calculating unit 13B may use the inertia moment, the mass of the bone portion, and the muscle Jacobian stored in the storage unit 16.

In the present embodiment, the first calculation unit 13B extracts the muscle portion from the CT image acquired by the first acquisition unit 12A. The first calculator 13B extracts the muscle region by extracting the region of the CT value indicating the soft tissue (muscle) from the CT image. Then, the first calculating unit 13B further calculates a feature amount indicating the length of the muscle portion from the feature points of the extracted muscle portion in the muscle region including the start portion and the stop portion with respect to the bone portion.

Then, the first calculation unit 13B arranges the three-dimensional shape of the muscle portion in the bone joint shape model showing the three-dimensional shapes of the joint portion and the bone portion, and adds the calculated positional relationship to the musculoskeletal model. To generate. In addition, the first calculation unit 13B adds a feature amount indicating the length of the muscle portion to a position corresponding to the corresponding muscle portion in the musculoskeletal model.

The second calculation unit 13C uses the positional relationship calculated by the first calculation unit 13B and the feature amount indicating the length of the muscle portion, and the acting force exerted by the muscle on the plurality of bone portions continuous to the joint portion. To calculate.

In the present embodiment, the second calculator 13C has at least one of the relationship between the muscle tension of the muscle connected to the bone, the torque acting on the joint, and the load and deformation of the soft tissue attached to the bone. Is calculated as the acting force. The relationship between the load and the deformation of the soft tissue attached to the bone part is, for example, the hardness of the soft tissue (tendon, cartilage, etc.) attached to the bone part.

Specifically, the second calculation unit 13C uses the positional relationship and the feature amount calculated by the first calculation unit 13B to perform the inverse dynamics in the same manner as the second calculation unit 12C of the first embodiment. By performing the calculation, the acting force exerted by the muscle on the joint is calculated.

Specifically, the second calculation unit 13C determines the second calculation unit 12C according to the first embodiment regarding the muscle tension of the muscles connected between the bones continuous with the joint and the torque acting on the joint. It is calculated in the same manner as.

In the present embodiment, the second calculation unit 13C determines the characteristic amount indicating the length of the muscle portion for the relation characteristic (for example, hardness of tendon or cartilage) between the load and the deformation of the soft tissue attached to the bone portion. Used to calculate by performing an inverse dynamics calculation. Note that the second calculator 13C stores the standard characteristics of the relationship between the load and the deformation of the soft tissue attached to the bone portion and the deformation in advance in the storage unit 16 (the load and the deformation of the soft tissue attached to the bone portion. It may be calculated by reading the (relationship characteristic of).

Through the above processing, the second calculation unit 13C performs the inverse dynamics calculation based on the positional relationship and the characteristic amount calculated by the first calculation unit 13B, and thereby the acting force (muscle tension) acting on the joint by the muscle. , The torque acting on the joint, and the relational characteristics between the load and the deformation of the soft tissue attached to the bone).

The third calculator 12F calculates the first stress acting on the joint based on the first dynamic model constructed by the constructer 12E and the acting force calculated by the second calculator 13C. That is, the third calculator 12F calculates the first stress of each element (each element in the FEM) on the contact surface between the bone and the joint, as in the first embodiment.

The second acquisition unit 13E acquires an artificial joint model. The artificial joint model indicates the three-dimensional shape of the artificial joint and the installation position of the artificial joint with respect to the bone part. The artificial joint model may further include parameters such as hardness of the artificial joint.

The second acquisition unit 13E acquires, for example, the artificial joint model from the input unit 14A. For example, the user operates the input unit 14A to input the three-dimensional shape and the installation position of the artificial joint. In the image analysis apparatus 11A, a known image creation software or the like may be used to generate the three-dimensional shape and the installation position of the artificial joint by the user operating the input unit 14A. Then, the second acquisition unit 13E acquires the artificial joint model from the input unit 14A. The artificial joint model may be stored in the storage unit 16 in advance. In this case, the second acquisition unit 13E may acquire the artificial joint model from the storage unit 16. The display control unit 13H may display a list of artificial joint models stored in the storage unit 16 on the display unit 14B. Then, when a desired artificial joint model is selected from the displayed list of artificial joint models by the user's operation instruction of the input unit 14A, the second acquisition unit 13E acquires the selected artificial joint model. You may.

FIG. 9 is a diagram schematically showing an example of the artificial joint model 23. For example, the artificial joint model 23 has a three-dimensional shape including an artificial joint 23C attached to the bone portion 22C (see FIG. 9A) and an artificial joint 23D attached to the bone portion 22D (see FIG. 9B). including. The artificial joint 23C and the artificial joint 23D are installed at, for example, the installation positions shown in FIG. 9C with respect to the bone portion 22C and the bone portion 22D.

The user operates the input unit 14A to input the three-dimensional shape of the artificial joint model 23 and the installation position of the artificial joint with respect to the bone part 22. As a result, the second acquisition unit 13E acquires the artificial joint model.

The three-dimensional shape and installation position of the artificial joint in the artificial joint model 23 can be appropriately changed by a user's operation instruction of the input unit 14A.

Returning to FIG. 8, the fourth calculating unit 13F deletes the shape model of the joint from the first dynamic model constructed by the constructing unit 12E, and replaces the shape model of the joint with the second obtaining unit 13E. A second mechanical model including the artificial joint model is constructed. Then, the fourth calculator 13F calculates the second stress acting on the artificial joint based on the constructed second dynamic model and the acting force calculated by the second calculator 13C.

Specifically, the fourth calculator 13F deletes the shape model showing the three-dimensional shape of the joint from the bone joint shape model showing the three-dimensional shapes of the bone and the joint included in the first dynamic model. Then, the fourth calculator 13F arranges the three-dimensional shape of the artificial joint indicated by the artificial joint model at the installation position indicated by the artificial joint model in the bone joint shape model excluding the shape model of the joint portion. Thereby, the fourth calculation unit 13F builds the second dynamic model.

Then, the fourth calculating unit 13F, based on the second dynamic model and the acting force calculated by the second calculating unit 13C, similarly to the third calculating unit 12F, the contact surface between the bone part and the artificial joint. The second stress of each element (each element in FEM) in is calculated.

It is assumed that the reception unit 12D receives at least one change instruction of the three-dimensional shape of the artificial joint and the installation position. In this case, the fourth calculation unit 13F re-creates the second dynamic model by adding to the first dynamic model an artificial joint model indicating at least one of the three-dimensional shape and the installation position of the artificial joint changed by the received change instruction. To construct. That is, the fourth calculation unit 13F reconstructs the second dynamic model in which at least one of the three-dimensional shape and the installation position of the artificial joint is changed according to the change instruction received by the reception unit 12D. Then, the fourth calculation unit 13F calculates the second stress based on the reconstructed second dynamic model and the acting force calculated by the second calculation unit 13C in the same manner as the third calculation unit 12F. ..

The first control unit 13D receives the change instruction and responds to the received change instruction until the second stress calculated by the fourth calculation unit 13F becomes less than the first stress calculated by the third calculation unit 12F. The reception unit 12D and the fourth calculation unit 13F are controlled so that the calculation of the second stress and the calculation of the second stress are repeatedly performed in this order.

The first control unit 13D, for example, for all the elements on the contact surface between the bone portion and the artificial joint, the reception unit until the second stress calculated for each element becomes less than the first stress corresponding to the same element. The control of 12D and the fourth calculation unit 13F is repeatedly executed. The first control unit 13D until at least one of all the elements on the contact surface between the bone part and the artificial joint has the second stress calculated for each element less than the first stress corresponding to the same element. The control of the reception unit 12D and the fourth calculation unit 13F may be repeatedly executed.

The state in which the second stress is less than the first stress indicates a state in which the stress acting on the joint part is reduced by the artificial joint.

The modeling control unit 13I controls the modeling by the modeling unit 15. In the present embodiment, when the second stress is less than the first stress, the modeling control unit 13I has a three-dimensional shape corresponding to the artificial joint model included in the second mechanical model used to calculate the second stress. The modeling unit 15 is controlled so as to model the artificial joint model.

Therefore, the modeling unit 15 models the three-dimensional artificial joint model in which the stress acting on the joint is reduced under the control of the modeling control unit 13I.

When the second stress is less than the first stress, the modeling control unit 13I includes the bone joint shape model (the three-dimensional shape of the joint portion is included in the second mechanical model used for calculating the second stress). The modeling unit 15 may be controlled so as to model both the bone part model of the bone part having a three-dimensional shape corresponding to the above) and the artificial joint model having a three-dimensional shape corresponding to the artificial joint model.

The generation unit 13G generates an analysis image including the first stress image and the second stress image.

As described in the first embodiment, the first stress image is an image showing the first stress acting on the joint calculated by the third calculator 12F. That is, the first stress image is a stress image in which the stress region in which the first stress acts on the contact surface between the bone portion and the joint portion of the subject is shown with the color density according to the strength of the first stress. As in the first embodiment, the color density indicates at least one of color and density.

The second stress image is an image showing the second stress acting on the artificial joint calculated by the fourth calculator 13F. That is, the second stress image is a stress image in which the stress region in which the second stress acts on the contact surface between the bone part of the subject and the artificial joint is shown by the color density according to the intensity of the second stress. is there.

In addition, the generation unit 13G displays an image showing the second stress when the second stress calculated by the fourth calculation unit 13F is less than the first stress calculated by the third calculation unit 12F as the second stress. It is preferable to generate it as an image.

The display control unit 13H controls the display unit 14B to display the analysis image 51 generated by the generation unit 13G and including the first stress image 30 and the second stress image 52 (see FIGS. 10 to 14).

FIG. 10 is a diagram showing an example of the analysis image 51. For example, the analysis image 51 includes the first stress image 30 and the second stress image 52.

As described in the first embodiment, the first stress image 30 acts on the bone image 40 and the stress region 42 in which the first stress acts on the contact surface between the bone and the joint. It is a stress image shown by the color density according to the intensity of stress. In addition, the first stress image 30 may further include a gauge 36 that indicates the color density corresponding to the strength of the first stress.

The second stress image 52 shows the bone part image 40 and the stress region 43 in which the second stress acts on the contact surface between the bone part and the artificial joint, with the color density corresponding to the strength of the second stress acting. It is a stress image. In addition, the second stress image 52 may further include a gauge 37 that indicates the color density corresponding to the intensity of the second stress.

In this way, by displaying the analysis image 51 including the first stress image 30 and the second stress image 52 on the display unit 14B, the stress applied to the joint portion before the operation (before the insertion of the artificial joint) and after the operation ( The stress applied to the artificial joint after the artificial joint is inserted) can be displayed side by side.

FIG. 11 is a schematic diagram showing another form of the analysis image 51. The analysis image 51 may further include at least one of the first dynamic model image 32 showing the first dynamic model and the second dynamic model image 35 showing the second dynamic model.

The first dynamic model image 32 includes the shape model image 44 and the gauge 38 as described in the first embodiment.

In the shape model image 44, the distribution and strength of the first stress acting on the contact surface between the bone portion and the joint portion are the same as those of the first stress image 30 included in the same analysis image 51. 3 is an image showing the positional relationship between the bone part 22 (22A, 22B) and the joint part 24 in a three-dimensional shape.

The gauge 38 is an image in which a list of color densities corresponding to the strength of the relationship characteristics between load and deformation and the values of the relationship characteristics corresponding to each color density are displayed in association with each other. The shape model image 44 is provided with a color density according to the value of the relationship characteristic between load and deformation.

The second dynamic model image 35 includes a shape model image 45 and a gauge 39.

In the shape model image 45, the distribution and strength of the second stress acting on the contact surface between the bone part and the artificial joint are the same as those of the second stress image 52 included in the same analysis image 51. 3 is an image showing the positional relationship between the bone part 22 (22A, 22B) and the artificial joint 25 in the three-dimensional shape.

The gauge 39 is an image in which a list of color densities according to the strength of the relationship characteristic between load and deformation and the value of the relationship characteristic corresponding to each color density are displayed in association with each other. The shape model image 45 is provided with a color density according to the value of the relationship characteristic between load and deformation.

The generation unit 13G generates the analysis image 51 including the first stress image 30, the first dynamic model image 32, the second stress image 52, and the second dynamic model image 35, so that the display unit 14B displays the analysis image 51. Displays the analysis image 51A shown in FIG. 11, for example.

Here, the generation unit 13G changes the positional relationship between the joint portion 24 and the bone portion 22, and the artificial joint 25 and the bone portion 22, and the first stress image 30 and the first dynamic model image corresponding to the change in the positional relationship. 32, the second stress image 52, and the second dynamic model image 35 may be generated.

For example, the generation unit 13G causes the joint portion 24 to move when the positional relationship between the joint portion 24 and the bone portion 22 and the artificial joint 25 and the bone portion 22 changes the joint angle between 180° and 45°. The first calculation unit 13B, the construction unit 12E, the second calculation unit 13C, the third calculation unit 12F, and the second acquisition unit 13E so as to calculate the first stress acting on the artificial joint 25 and the second stress acting on the artificial joint 25. , 4th calculation part 13F, and 1st control part 13D are controlled. Then, the generation unit 13G acquires the distribution of the first stress according to the joint angle from the third calculation unit 12F. In addition, the generation unit 13G acquires the distribution of the second stress according to the joint angle from the fourth calculation unit 13F.

It is assumed that the time-series CT images acquired by the first acquisition unit 12A are images in which the joint angle is changed (for example, changed between 180° and 45°). In this case, by using each of the time-series CT images acquired by the first acquisition unit 12A, the first calculation unit 13B, the construction unit 12E, the second calculation unit 13C, the third calculation unit 12F, the second acquisition unit 13E, The fourth calculation unit 13F and the first control unit 13D perform the above processing, and calculate the distribution of the first stress and the distribution of the second stress according to each joint angle. Therefore, in this case, the generation unit 13G may acquire the distribution of the first stress corresponding to the joint angle from the third calculation unit 12F and the distribution of the second stress from the fourth calculation unit 13F.

Then, the generation unit 13G generates the first stress image 30 and the second stress image 52 corresponding to each joint angle. The display control unit 13H displays the analysis image 51 including the first stress image 30 and the second stress image 52 generated by the generation unit 13G on the display unit 14B. At this time, the generation unit 13G generates the first dynamic model image 32 and the second dynamic model image 35, and the first stress image 30, the first dynamic model image 32, the second stress image 52, and the second dynamic model. The analysis image 51 including the model image 35 may be generated.

In this case, the display control unit 13H displays the analysis image 51 on the display unit 14B, so that, for example, the analysis image 51 illustrated in FIGS. 11, 12, and 13 is displayed on the display unit 14B.

FIG. 11 shows an analysis image 51A including a first dynamic model image 32A, a first stress image 30A, a second stress image 52A, and a second dynamic model image 35A when the joint angle is about 180°. It is a figure which shows an example. In the example shown in FIG. 11, the stress region 42 is indicated by the color density (36 ₁₄ ) indicating the first stress “0”, which is indicated by the gauge 36. The stress region 43 is indicated by the color density (37 ₁₄ ) indicating the second stress “0”.

FIG. 12 shows an analysis image 51B including the first dynamic model image 32B, the first stress image 30B, the second stress image 52B, and the second dynamic model image 35B when the joint angle is about 120°. It is a figure which shows an example.

In the example shown in FIG. 12, at the interface between the bone and joint portions, the stress regions 42 ₁ are indicated by the color density 36 ₁ showing a first stress "8 × 10 ^-1", the stress area 42 _5, is indicated by the color density 36 ₅ showing a first stress "5.333 × ^{10 -1",} it stressed areas 42 ₈ is indicated by the color density 36 ₈ showing a first stress "4.0 × ^{10 -1",} The outermost stress region 42 ₁₄ is shown with a color density 36 ₁₄ indicating the first stress “0”.

Further, in the example shown in FIG. 12, at the interface between the bone and the artificial joint, stress regions 43 ₁ are indicated by the color density 37 ₁ showing a second stress "8 × 10 ^-1", stress regions 43 ₅ is indicated by the color density 37 ₅ showing a second stress "5.333 × ^{10 -1",} it stressed areas 43 _8, shown in color density 37 ₈ showing a second stress "4.0 × ^{10 -1"} The outermost stress region 43 ₁₄ is indicated by the color density 37 ₁₄ indicating the second stress “0”.

As shown in FIG. 12, as compared with the stress region 42 in which the first stress acts as shown in the first stress image 30B, the stress region 43 in which the second stress acts as shown in the second stress image 52B has a higher stress intensity. Is weak, and the range where strong stress acts is narrow. Further, in FIG. 12, the first dynamic model image 32B and the second dynamic model image 35B included in the analysis image 51B are images showing that the angle between the bone portion 22A and the bone portion 22B is approximately 120°. ing.

FIG. 13 shows an analysis image 51C including a first dynamics model image 32C when the joint angle is about 90°, a first stress image 30C, a second stress image 52C, and a second dynamics model image 35C. It is a figure which shows an example. In the example shown in FIG. 13, as in FIG. 12, the stress regions 42 and the stress regions 43 are represented by color densities corresponding to the strengths of the first stress and the second stress that act. Note that the stress regions 42 and 43 shown in FIG. 13 have a wider range of regions where the first stress and the second stress are stronger than the color densities of the stress regions 42 and 43 shown in FIG. ..

Further, in FIG. 13, the first dynamic model image 32C and the second dynamic model image 35C included in the analysis image 51C are images showing that the angle between the bone portion 22A and the bone portion 22B is about 90°. ing.

As described above, the generation unit 13G causes the first stress image 30 (first stress images 30A, 30B, 30C) and the second stress image 52 (second stress image) according to the change in the positional relationship between the joint portion 24 and the bone portion 22. Stress images 52A, 52B, 52C) are generated. For this reason, the image analysis device 11A determines the position where the first stress and the second stress of each strength act on each of the contact surface between the bone portion and the joint portion and the contact surface between the bone portion and the artificial joint, and The range can be easily provided to the user.

Note that, like the display control unit 12H of the first embodiment, the display control unit 13H selectively selects the stress region 42 of the first stress and the stress region 43 of the second stress of the strength designated by the user. The first stress image 30 and the second stress image 52, which are included, may be displayed on the display unit 14B.

Further, similarly to the display control unit 12H of the first embodiment, the display control unit 13H selects the stress region 42 of the first stress and the stress region 43 of the second stress in the range of the strength designated by the user. The first stress image 30 and the second stress image 52 that are included in the image may be displayed on the display unit 14B.

Next, the procedure of the image analysis process executed by the image analysis apparatus 11A will be described. FIG. 14 is a flowchart showing the procedure of the image analysis process executed by the image analysis apparatus 11A.

First, it is determined whether the receiving unit 12D has received the analysis instruction from the input unit 14A (step S200). For example, the user operates the input unit 14A to instruct image analysis, display of the analysis image, or modeling instruction. When receiving the signal indicating the image analysis from the input unit 14A, the reception unit 12D determines that the analysis instruction has been received (step S200: Yes).

When a positive determination is made in step S200 (step S200: Yes), the first acquisition unit 12A acquires a CT image (step S202).

Next, the building unit 12E builds a first dynamic model from the CT image acquired in step S202 (step S204).

Next, the 1st calculation part 13B calculates the positional relationship of the several bone part which follows a joint part using the CT image acquired by step S202 (step S206).

Next, the 1st calculation part 13B extracts a muscle part from the CT image acquired by step S202 (step S208). Next, the 1st calculation part 13B calculates the feature-value which shows the length of a muscle part from the characteristic point of the extracted muscle part containing the start part and stop part with respect to a bone part (step S210). Then, the first calculation unit 13B arranges the three-dimensional shape of the muscle portion in the bone joint shape model showing the three-dimensional shapes of the joint portion and the bone portion, and adds the calculated positional relationship to the musculoskeletal model. To generate. In addition, the first calculation unit 13B adds a feature amount indicating the length of the muscle portion to a position corresponding to the corresponding muscle portion in the musculoskeletal model.

Next, the second calculation unit 13C uses the positional relationship calculated by the first calculation unit 13B and the feature amount indicating the length of the muscle portion to act on the bone portion continuous to the joint portion by the muscle. The force is calculated (step S212).

Next, the third calculation unit 12F acts on the joint based on the first dynamic model constructed by the construction unit 12E in step S204 and the acting force calculated by the second calculation unit 13C in step S212. One stress is calculated (step S214).

Next, the generation unit 13G generates a first stress image indicating the first stress calculated in step S214 (step S216). In addition, in step S216, the generation unit 13G may simultaneously generate the first dynamic model image corresponding to the first stress image.

Next, the generation unit 13G stores the generated first stress image in the storage unit 16 (step S218). In step S218, the generation unit 13G preferably stores the first stress image generated in step S216 in the storage unit 16 in association with the identification information for identifying the first stress image. This identification information is, for example, at least one of the subject ID of the subject of the CT image acquired in step S202, the date and time of the CT image, the date and time of generation of the analysis image, and the joint angle of the joint included in the CT image. It is preferable to include one.

Next, the second acquisition unit 13E acquires the artificial joint model input by the operation of the input unit 14A by the user (step S220).

Next, the fourth calculating unit 13F deletes the shape model of the joint from the first dynamic model constructed by the constructing unit 12E in Step S204, replaces the shape model of the joint with the second obtaining unit in Step S220. The second mechanical model including the artificial joint model acquired by 13E is constructed (step S222). Then, the fourth calculation unit 13F calculates the second stress acting on the artificial joint based on the constructed second dynamic model and the acting force calculated by the second calculation unit 13C in step S212 (step S224). ).

Next, the first control unit 13D determines whether the second stress calculated in step S224 is less than the first stress calculated in step S214 (step S226).

When the 2nd stress is more than the 1st stress (Step S226: No), it progresses to Step S232. In step S232, the acceptance unit 12D repeats the negative determination until accepting at least one change instruction of the three-dimensional shape of the artificial joint and the installation position (step S232: No). In step S232, for example, the first control unit 13D controls the display control unit 13H to display the acceptance screen for the instruction to change at least one of the three-dimensional shape and the installation position of the artificial joint on the display unit 14B. For example, the user inputs a change instruction for at least one of the three-dimensional shape of the artificial joint and the installation position by operating the input unit 14A while referring to the reception screen. Then, the reception unit 12D receives the change instruction.

If an affirmative decision is made in step S232 (step S232: Yes), the operation proceeds to step S234. In step S234, the fourth calculation unit 13F changes at least one of the three-dimensional shape and the installation position of the artificial joint according to the change instruction received by the reception unit 12D in step S232 (step S234), and after the change, 2 The dynamic model is reconstructed (step S236). Then, the fourth calculator 13F calculates the second stress based on the second dynamic model reconstructed in step S236 and the acting force calculated by the second calculator 13C in step S212 (step S237). .. Then, the process returns to step S226.

Until the second stress calculated by the fourth calculator 13F becomes less than the first stress calculated by the third calculator 12F (step S226: Yes), the first controller 13D performs the processes of steps S226 to S237. The reception unit 12D and the fourth calculation unit 13F are controlled so as to repeatedly execute. Then, if an affirmative decision is made in step S226 (step S226: Yes), the operation proceeds to step S228.

In step S228, the generation unit 13G generates a second stress image indicating the second stress when it is determined to be less than the first stress in step S226 (step S228). In addition, in step S228, the generation unit 13G may simultaneously generate the second dynamic model image corresponding to the second stress image.

Next, the generation unit 13G stores the generated second stress image in the storage unit 16 (step S230). Then, this routine ends. In addition, in step S230, the generation unit 13G preferably stores the second stress image generated in step S228 in the storage unit 16 in association with the identification information used when the first stress image is stored in step S218.

On the other hand, when the receiving unit 12D makes a negative determination in step S200 (step S200: No), the process proceeds to step S238. In step S238, the reception unit 12D determines whether or not the signal indicating the instruction to display the analysis image is received from the input unit 14A.

If it is determined that the signal indicating the instruction to display the analysis image has been received (step S238: Yes), the process proceeds to step S240.

In step S240, the display control unit 13H reads the analysis image stored in the storage unit 16 (step S240). Then, the display control unit 13H performs control to display the read analysis image (including the first stress image 30 and the second stress image 52) on the display unit 14B (step S242). Then, this routine ends.

On the other hand, when a negative determination is made in step S238 (step S238: No), the process proceeds to step S244. In step S244, the reception unit 12D determines whether the modeling instruction is received from the input unit 14A. If it is determined that the molding instruction has been received (step S244: Yes), the process proceeds to step S246.

In step S246, when the second stress is less than the first stress, the modeling control unit 13I generates an artificial three-dimensional shape corresponding to the artificial joint model included in the second mechanical model used to calculate the second stress. The modeling unit 15 is controlled so as to model the joint model (step S246). Then, this routine ends. Therefore, the modeling unit 15 models the three-dimensional artificial joint model in which the stress acting on the joint is reduced under the control of the modeling control unit 13I.

In addition, in step S246, the display control unit 13H may display the list of the second stress images stored in the storage unit 16 on the display unit 14B. Then, when the second stress image desired by the user is selected by the operation of the input unit 14A by the user, the modeling control unit 13I uses the second stress image indicated by the selected second stress image to calculate the second stress. The modeling unit 15 may be controlled so as to model an artificial joint model included in the two-dynamic model and corresponding to the artificial joint model.

If a negative determination is made in step S244 (step S244: No), this routine ends.

As described above, the image analysis device 11A of the present embodiment includes the first acquisition unit 12A, the construction unit 12E, the first calculation unit 13B, the second calculation unit 13C, and the third calculation unit 12F. The second acquisition unit 13E and the fourth calculation unit 13F are provided.

The first acquisition unit 12A acquires an image of a joint part of a subject and a bone part continuous to the joint part. The constructing unit 12E constructs a first dynamic model showing the three-dimensional shapes of the bone and joint and the relational characteristics of the load and deformation in the bone and joint from the image. The first calculator 13B calculates the positional relationship between the bones that are continuous with the joint. The second calculator 13C calculates the acting force exerted by the muscle on the bone part continuous to the joint part from the positional relationship. The third calculator 12F calculates the first stress acting on the joint based on the first dynamic model and the acting force. The second acquisition unit 13E acquires an artificial joint model indicating the three-dimensional shape and the installation position of the artificial joint. The fourth calculator 13F calculates the second stress acting on the artificial joint based on the second mechanical model obtained by adding the artificial joint model to the first mechanical model and the acting force.

As described above, the image analysis apparatus 11A of the present embodiment uses the action force exerted by the muscle on the bone part continuous to the joint part and the first dynamic model, as in the first embodiment. , The first stress acting on the joint is calculated. Therefore, the image analysis device 11A according to the present embodiment can calculate the stress acting on the joint part, in consideration of the force acting by the muscle.

Further, the image analysis device 11A of the present embodiment calculates the second stress acting on the artificial joint using the acting force and the artificial joint model.

Therefore, in the image analysis apparatus 11A of the present embodiment, the stress acting on the joint part of the subject can be calculated with high accuracy, and the stress (first stress, second stress) before and after the installation of the artificial joint can be calculated. It can be calculated with high accuracy. Therefore, the image analysis device 11A of the present embodiment can be suitably used for a simulation before surgery for installing an artificial joint.

(Third Embodiment)
In the present embodiment, an image captured in a first load state due to a load on a site including a joint part to be analyzed in the subject and a second load state in which the subject has a smaller load than the first load state A case where a captured image and a captured image are acquired will be described.

The first load state refers to a state in which a predetermined load is applied to a part of the subject including a joint part to be analyzed. The second load state refers to a state in which a load smaller than the first load state is applied to a portion of the subject including the joint part to be analyzed.

The load applied in the first load state may include a plurality of types of loads having different values, instead of one type. Similarly, the load applied in the second load state may include a plurality of types of loads having different values instead of one type. It should be noted that the second load state includes a state without load (that is, a state where the load is “0”).

FIG. 15 is a configuration diagram of the image analysis apparatus 11B of the present embodiment. The image analysis device 11B is connected to the external device 60. The external device 60 is a device that captures an image to be analyzed by the image analysis device 11B. The image analysis device 11B may include the external device 60.

FIG. 16 is a schematic diagram showing an example of the external device 60. The external device 60 includes an imaging unit 60A, a support base 62, a drive unit 60B, a communication unit 60C, a control unit 60D, a fixing unit 66, a load applying unit 64, a pressure sensor 65, and a guide member 63. , Is provided. The control unit 60D controls the external device 60. The control unit 60D is connected to the image capturing unit 60A, the driving unit 60B, the communication unit 60C, and the pressure sensor 65 so that data and signals can be exchanged.

The support base 62 is a base that supports the subject H. The support base 62 is provided with a long guide member 63 along the longitudinal direction of the support base 62. The guide member 63 is provided with a drive unit 60B and a load applying unit 64. The load applying portion 64 is provided so as to be movable along the longitudinal direction of the guide member 63. The drive unit 60B reciprocates the load applying unit 64 in the longitudinal direction of the guide member 63. The fixed portion 66 is fixed to the support base 62.

For example, it is assumed that the subject H lies on the support table 62. Then, the fixing portion 66 is fixed to, for example, the waist of the subject H or the like. In this state, if the load applying section 64 is moved along the guide member 63 in the direction approaching the fixed section 66 under the control of the control section 60D, the subject H will be under a load. The load applied to the subject H is detected by the pressure sensor 65. Further, when the load loading section 64 is moved along the guide member 63 in the direction away from the fixed section 66 under the control of the control section 60D, the subject H is released from the loaded state. It should be noted that the subject H, the fixing portion 66, and the load applying portion are arranged so that the fixing portion 66 and the load applying portion 64 are positioned so as to sandwich a region including the analysis target region (for example, knee) of the subject H. The position of 64 may be adjusted in advance.

The image capturing unit 60A captures CT images and MR images. The imaging unit 60A is provided so as to be movable in the longitudinal direction of the support base 62 by a drive mechanism (not shown). Therefore, the imaging unit 60A, under the control of the control unit 60D, an image captured in the first load state due to the load and an image captured in the second load state due to the load, in at least the analysis target region of the subject H. , Can be photographed.

The communication unit 60C communicates with the control unit 17 of the image analysis device 11B. Therefore, the communication unit 60C transmits an image (for example, a CT image) captured by the image capturing unit 60A to the image analysis device 11B.

Returning to FIG. 15, the image analysis device 11B includes a control unit 17, a UI unit 14, a storage unit 16, and a modeling unit 15. The UI unit 14, the storage unit 16, the modeling unit 15, and the external device 60 are connected to the control unit 17 so that data and signals can be exchanged.

The UI unit 14, the storage unit 16, and the modeling unit 15 are the same as those in the second embodiment.

The control unit 17 controls the image analysis device 11B. The control unit 17 includes a first acquisition unit 17A, a second control unit 17B, a first calculation unit 13B, a second calculation unit 17C, a first control unit 13D, a reception unit 12D, and a construction unit 12E. The third calculator 12F, the second acquirer 13E, the fourth calculator 13F, the generator 13G, the display controller 13H, and the modeling controller 13I are included.

First acquisition unit 17A, second control unit 17B, first calculation unit 13B, second calculation unit 17C, first control unit 13D, reception unit 12D, construction unit 12E, third calculation unit 12F, second acquisition unit 13E, Part or all of the fourth calculation unit 13F, the generation unit 13G, the display control unit 13H, and the modeling control unit 13I may be realized by causing a processing device such as a CPU to execute a program, that is, by software. However, it may be realized by hardware such as an IC, or may be realized by using software and hardware together.

1st calculation part 13B, 1st control part 13D, acceptance part 12D, construction part 12E, 3rd calculation part 12F, 2nd acquisition part 13E, 4th calculation part 13F, generation part 13G, display control part 13H, and modeling control. The part 13I is the same as that of the second embodiment.

The first acquisition unit 17A acquires an image (in the present embodiment, a case of a CT image will be described) regarding a joint part of a subject and a bone part continuous to the joint part. In the present embodiment, the first acquisition unit 17A, from the external device 60, a CT image (referred to as a first image) taken in a second load state on a region of the subject including a joint to be analyzed, A CT image (referred to as a second image) taken in the first load state and the external device 60 are acquired.

In the present embodiment, as an example, a case where the second load state is a state in which no load is applied will be described. However, as described above, the second load state may be a load state in which the load is smaller than the first load state, and is not limited to this example.

The second control unit 17B, for example, a first image captured in a state in which no load is applied (a second load state) to a site including a joint part to be analyzed in the subject, and a state in which the site is loaded. The external device 60 is controlled to capture the second image captured in the (first load state). Note that the second control unit 17B adjusts the strength of the load to take images in a state in which a plurality of types of loads are loaded (a plurality of first load states) and a plurality of second load states. The external device 60 may be controlled so as to capture a plurality of first images and a plurality of second images.

When the control unit 60D of the external device 60 receives the imaging instruction from the second control unit 17B, the control unit 60D controls the driving unit 60B and the imaging unit 60A so as not to apply a load to the subject H (second load state). The first image is obtained by shooting. Further, the control unit 60D controls the drive unit 60B and the imaging unit 60A to perform imaging in a state where the load is applied to the subject H (first load state), and a second image is obtained.

It should be noted that the state in which a load is applied means a state in which a predetermined pressure value (load) is detected by the pressure sensor 65, for example. The control unit 60D controls the drive unit 60B so as to move the load loading unit 64 in a direction approaching the fixed unit 66 until the pressure value is detected by the pressure sensor 65, and when the pressure value is detected, The image capturing unit 60A is controlled so as to perform image capturing. The control unit 60D may control not only the load applied to the joint portion but also the movable range of the joint. In addition to the pressure sensor, the control unit 60D may detect the load using a device that can directly measure the load (for example, a load cell).

Then, the control unit 60D uses the obtained image as the second image. Further, the control unit 60D controls the drive unit 60B so as to move the load loading unit 64 in the direction away from the fixed unit 66 until the pressure value detected by the pressure sensor 65 becomes "0", and the pressure value "0". When "" is detected, the image capturing unit 60A is controlled to perform image capturing. Then, the obtained image is treated as the first image. Then, the communication unit 60C transmits the obtained first image and second image to the image analysis device 11B. As a result, the first acquisition unit 17A obtains the first image and the second image.

The first calculation unit 13B, the first control unit 13D, the reception unit 12D, the construction unit 12E, the third calculation unit 12F, the second acquisition unit 13E, the fourth calculation unit 13F, the generation unit 13G, the display control unit 13H, and The modeling control unit 13I may execute the same processing as that in the second embodiment using the first image (image captured in the second load state where no load is applied) as the CT image.

The second calculator 17C uses the positional relationship calculated by the first calculator 13B, the characteristic amount indicating the length of the muscle portion, and the pressure value acquired by the pressure sensor 65 (that is, the load applied at the time of imaging). , The acting force exerted by the muscle on a plurality of bone parts continuous to the joint part is calculated.

In the present embodiment, the second calculating unit 17C has at least one of the relationship between the muscle tension of the muscle connected to the bone, the torque acting on the joint, and the load and deformation of the soft tissue attached to the bone. Is calculated as the acting force. The relationship between the load and the deformation of the soft tissue attached to the bone part is, for example, the hardness of the soft tissue (tendon, cartilage, etc.) attached to the bone part.

Specifically, the second calculation unit 17C uses the positional relationship and the feature amount calculated by the first calculation unit 13B to perform the inverse dynamics in the same manner as the second calculation unit 12C of the first embodiment. By performing the calculation, the acting force exerted by the muscle on the joint is calculated.

In the second embodiment, the second calculating unit 13C stores in advance the storage unit 16 with respect to the relationship characteristic between the load and the deformation of the soft tissue attached to the bone (for example, the hardness of tendon or cartilage). It was explained that the calculation may be performed by reading the standard hardness (relationship characteristic between load and deformation of soft tissue attached to bone).

On the other hand, in the present embodiment, the second calculating unit 17C calculates the relationship characteristic between the load and the deformation of the soft tissue attached to the bone using the first image and the second image acquired by the first acquiring unit 17A. To do.

For example, the second calculator 17C uses the length of the soft tissue extracted from the first image, the length of the same soft tissue extracted from the second image, and the load applied by the external device 60 at the time of capturing the second image. By performing known calculation, the relational characteristic between the load and the deformation of the soft tissue attached to the bone part is calculated.

It should be noted that, when the second calculator 17C acquires a plurality of second images having different loads applied at the time of imaging, for each of the plurality of second images, the length of the soft tissue extracted from the first image and the second Using the same soft tissue length extracted from the image and the load applied by the external device 60 at the time of capturing the second image, a well-known calculation is performed to determine the load and deformation of the soft tissue attached to the bone part. The relationship characteristic may be calculated.

Next, the procedure of the image analysis process executed by the image analysis device 11B will be described. FIG. 17 is a flowchart showing the procedure of the image analysis process executed by the image analysis device 11B.

First, the receiving unit 12D determines whether or not the analysis instruction is received from the input unit 14A (step S300). The process of step S300 is the same as the process of step S200 (see FIG. 14).

When a positive determination is made in step S300 (step S300: Yes), the first acquisition unit 17A acquires the first image from the external device 60 (step S302).

Next, the second control unit 17B transmits a load signal instructing acquisition of the loaded second image to the external device 60 (step S304). The external device 60 that has received the load signal, under the control of the control unit 60D, takes an image in a first load state in which a load of a predetermined pressure value is applied to a region of the subject including a joint part to be analyzed, Get the image.

Next, the first acquisition unit 17A acquires the second image from the external device 60 (step S306). The first acquisition unit 17A stores the first image acquired in step S302 and the second image acquired in step S306 in the storage unit 16 (step S308).

Next, the control unit 17 is similar to steps S204 to S246 of the second embodiment, except that the first image acquired in step S302 is used instead of the CT image used in the second embodiment. Then, the processing of steps S310 to S352 is executed. Then, this routine ends.

Here, the relationship characteristic between the load and the deformation of the soft tissue attached to the bone part may vary greatly depending on the subject.

On the other hand, in the image analysis apparatus 11B according to the present embodiment, the first image captured in the second load state in which the load is smaller than the first load state in the site including the analysis target in the subject and the load in the site Using the second image captured in the first load state, the relationship characteristic between the load and the deformation of the soft tissue attached to the bone part is calculated. Then, the image analysis apparatus 11B performs the same processing as that in the second embodiment.

Therefore, the image analysis apparatus 11B of the present embodiment can calculate the first stress acting on the joint of the subject with higher accuracy than in the above-described embodiments.

(Fourth Embodiment)
Next, the hardware configuration of the image analysis devices 10, 11A, and 11B of the above-described embodiment will be described. FIG. 18 is a block diagram showing a hardware configuration example of the image analysis devices 10, 11A, and 11B of the above-described embodiment.

The image analysis devices 10, 11A, and 11B of the above-described embodiments include a CPU 800, a ROM (Read Only Memory) 820, a RAM (Random Access Memory) 840, an HDD (Hard Disk Drive) (not shown), and a communication I/F (not shown). Interface) 860. The CPU 800, the ROM 820, the RAM 840, the HDD (not shown), and the communication I/F 860 are interconnected by a bus, and have a hardware configuration using a normal computer.

A program for executing the image analysis processing executed by the image analysis devices 10, 11A, and 11B of the above-described embodiments is provided by being pre-installed in the ROM 820 or the like.

The program for executing the image analysis processing executed by the image analysis apparatuses 10, 11A, and 11B of the above-described embodiments is a CD-ROM, which is a file in a format installable or executable in these apparatuses, It may be configured to be provided by being recorded in a computer-readable recording medium such as a floppy (registered trademark) disk (FD), a CD-R, a DVD (Digital Versatile Disk).

Further, a program for executing the image analysis processing executed by the image analysis apparatus 10, 11A, 11B according to the above-described embodiment is stored in a computer connected to a network such as the Internet and is downloaded via the network. It may be configured to be provided by. Further, the program for executing the image analysis processing executed by the image analysis apparatus 10, 11A, 11B of the above-described embodiment may be provided or distributed via a network such as the Internet.

The program for executing the image analysis processing executed by the image analysis devices 10, 11A, and 11B of the above-described embodiment has a module configuration including the above-described functional units. As actual hardware, the CPU 800 reads each program from a storage medium such as the ROM 820 and executes the program to load the above functional units onto the main storage device and generate them on the main storage device.

<Modification>
In the above embodiment, the case where the third calculation unit 12F in the image analysis device 10, 11A, 11B calculates the first stress acting on the joint based on the first dynamic model and the acting force will be described. did. However, the third calculator 12F may calculate the first pressure acting on the joint portion instead of or together with the first stress. Regarding the calculation of the first pressure, the third calculator 12F may calculate the first pressure in the same manner as the first stress.

Moreover, in the said embodiment, the case where the 4th calculation part 13F in image analysis apparatus 11A, 11B calculated the 2nd stress which acts on an artificial joint based on a 2nd dynamic model and an acting force was demonstrated. However, the fourth calculator 13F may calculate the second pressure acting on the artificial joint instead of or together with the second stress. Regarding the calculation of the second pressure, the fourth calculator 13F may calculate the second pressure in the same manner as the second stress.

The image analysis devices 10, 11A, and 11B of the above embodiments can be applied to any type of image analysis device equipped with an imaging mechanism for imaging a subject. The image analysis apparatuses 10, 11A, and 11B of the above-described embodiments are, for example, an X-ray computed tomography apparatus (X-ray CT apparatus), a magnetic resonance diagnostic apparatus, an ultrasonic diagnostic apparatus, a SPECT (Single Photon Emission CT) apparatus, a PET. (Positron Emission Tomography) device, radiotherapy device, etc.

Further, in the above-described embodiment, the subject is assumed to be a human body. However, the subject may be an object other than the human body. For example, the subject may be shoes. In this case, the joint part of the object may be a part that is located between two parts where the rigidity of the object is equal to or greater than a threshold value. Further, the bone part that is continuous with the joint part may be a part that is continuous with the part corresponding to the joint part and has a rigidity equal to or higher than a threshold value. Further, the acting force exerted by the muscle on the bone part continuous to the joint part is applied to the part corresponding to the bone part continuous to the part corresponding to the joint part in the object (for example, an object other than the part corresponding to the bone part). The force may be a force exerted by a reinforcing member or the like).

Therefore, the image analysis devices 10, 11A, and 11B of the above-described embodiments are applicable even when an object other than the human body is used as the subject.

Further, as described above, the image analysis devices 10, 11A, and 11B of the above-described embodiments include the construction unit 12E, the second calculation units 12C and 13C, the third calculation unit 12F, and the display control units 12H and 13H. And (see FIGS. 1, 8, and 15). The constructing unit 12E constructs a first dynamic model showing the three-dimensional shapes of the bone and joint and the relational characteristics between load and deformation from the image. The second calculators 12C and 13C calculate the acting force exerted by the muscle on the bone part from the positional relationship of the bone part. The third calculator 12F calculates the first stress acting on the joint based on the first dynamic model and the acting force. The display control unit 13H displays the first stress image showing the first stress on the display unit 14B.

Therefore, in addition to the effects of the above-described embodiments, the image analysis devices 10, 11A, and 11B of the above-described embodiments further include the strength of the first stress and the first stress at the contact surface between the bone part and the joint part. It is possible to easily provide the user with the position and the range in which the action of the item.

Although the embodiment has been described above, the embodiment and the modified examples are presented as examples, and are not intended to limit the scope of the invention. These new embodiments and modifications can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope of equivalents thereof.

10, 11A, 11B Image analysis device 12A, 17A 1st acquisition part 12B, 13B 1st calculation part 12C, 13C, 17C 2nd calculation part 12D reception part 12E construction part 12F 3rd calculation part 12G, 13G generation part 12H, 13H. Display control unit 13D First control unit 13E Second acquisition unit 13F Fourth calculation unit 13I Modeling control unit 14B Display unit 15 Modeling unit 17B Second control unit

Claims (17)

A first acquisition unit that acquires a CT image of a joint part of a subject and a bone part continuous to the joint part;
A construction unit that constructs from the CT image a three-dimensional shape of the bone portion and the joint portion, and a relationship characteristic between load and deformation in the bone portion and the joint portion,
A first calculation unit that calculates a positional relationship between the bone portions that are continuous with the joint portion;
A second calculation unit that calculates, based on the positional relationship, an acting force exerted by a muscle on the bone portion that is continuous with the joint portion;
A third calculation unit that calculates a first stress that acts on the joint based on the first dynamic model that shows the three-dimensional shape and the relationship characteristic, and the acting force;
Image analysis device equipped with. The construction unit is
The continuous or attached to the bone portion or the joint portion included before Symbol C T images, tendons, ligaments, and the deformation of the cartilage image analysis, first the load and deformation of the tendon, ligaments, and cartilage In addition to build a 2 relational characteristics,
The third calculator calculates the first stress acting on the joint based on the first dynamic model showing the three-dimensional shape, the relationship characteristic, and the second relationship characteristic, and the acting force. The image analysis device according to claim 1. The construction unit is
Regarding the living tissue other than the bone portion and the joint portion, which is less likely to be deformed by factors other than the load and in which the deformation caused by the load can be extracted, the second relation characteristic between the load and the deformation is further added. Build and
The third calculator calculates the first stress acting on the joint based on the three-dimensional shape, the relationship characteristic, the second relationship characteristic, and the acting force.
The image analysis apparatus according to claim 1. The third calculation unit, and the three-dimensional shape, and the relationship characteristics, and the acting force, on the basis of the calculated distribution of the first stress acting on the joint portion, claims 1 to 3 The image analysis device according to any one of 1 . The second calculator performs an inverse dynamics calculation using said positional relationship, to calculate the applied force, the image analysis apparatus according to any one of claims 1 to 4. The first calculation unit
A muscle portion is extracted from the CT image, and from a feature point including a start portion and a stop portion of the muscle portion with respect to the bone portion, a feature amount indicating the length of the muscle portion is further calculated,
The second calculation unit
Inverse power calculation is performed using the positional relationship and the feature amount to calculate the acting force.
The image analysis device according to any one of claims 1 to 5 . The acting force includes at least one of a muscle tension of the muscle connected to the bone portion, a relationship characteristic between a load and deformation of a soft tissue connected to the bone portion, and a torque acting on the joint portion,
The image analysis apparatus according to any one of claims 1 to 6. A second acquisition unit for acquiring an artificial joint model indicating the three-dimensional shape and installation position of the artificial joint;
A second stress acting on the artificial joint is calculated based on the second mechanical model obtained by adding the artificial joint model to the first mechanical model showing the three-dimensional shape and the relationship characteristic, and the acting force. A fourth calculator,
The image analysis apparatus according to any one of claims 1 to 7, further comprising: A receiving unit that receives at least one change instruction of the three-dimensional shape of the artificial joint and the installation position;
The fourth calculator is
The second dynamic model in which the artificial joint model showing at least one of the three-dimensional shape and the installation position of the artificial joint changed by the received change instruction is added to the first dynamic model, and the acting force. And calculating the second stress acting on the artificial joint,
The image analysis device according to claim 8. Until the calculated second stress becomes less than the first stress, the reception of the change instruction and the calculation of the second stress according to the received change instruction are repeatedly performed in this order. The image analysis apparatus according to claim 9, further comprising: a first control unit that controls the unit and the fourth calculation unit. When the calculated second stress is less than the first stress, a three-dimensional model is formed so as to form an artificial joint model corresponding to the artificial joint model included in the second mechanical model used for calculation. The image analysis apparatus according to claim 8, further comprising a modeling control unit that controls the modeling unit that performs printing. The third calculator calculates the first stress acting on the joint or the first pressure acting on the joint based on the first dynamic model and the acting force.
The image analysis device according to claim 8. The fourth calculator calculates a second stress acting on the artificial joint or a second pressure acting on the artificial joint based on the second dynamic model and the acting force.
The image analysis device according to claim 8. The first acquisition unit,
Acquiring the CT image including an image photographed in the subject under a first load condition due to a load and an image photographed in the subject under a second load condition in which the load is smaller than the first load condition. ,
The construction unit is
From the CT image , a three-dimensional shape of the bone part and the joint part and the relationship characteristic between the load and the deformation applied to the bone part and the joint part at the time of imaging are constructed.
The image analysis device according to any one of claims 1 to 13. Acquiring CT images of a joint part of a subject and a bone part continuous to the joint part;
Constructing from the CT image a three-dimensional shape of the bone part and the joint part, and a relationship characteristic between load and deformation in the bone part and the joint part ;
Calculating a positional relationship between the bone parts continuous to the joint part;
From the positional relationship, a step of calculating an acting force exerted by a muscle on the bone part continuous to the joint part,
Calculating a first stress acting on the joint based on the first dynamic model showing the three-dimensional shape and the relationship characteristic, and the acting force;
Image analysis method including. Acquiring CT images of a joint part of a subject and a bone part continuous to the joint part;
Constructing from the CT image a three-dimensional shape of the bone part and the joint part, and a relationship characteristic between load and deformation in the bone part and the joint part ;
Calculating a positional relationship between the bone parts continuous to the joint part;
From the positional relationship, a step of calculating an acting force exerted by a muscle on the bone part continuous to the joint part,
Calculating a first stress acting on the joint based on the first dynamic model showing the three-dimensional shape and the relationship characteristic, and the acting force;
A program that causes a computer to execute. A construction unit that constructs a three-dimensional shape of the bone and joint from the CT image, and a relationship characteristic between the load and deformation in the bone and joint .
A second calculation unit that calculates an acting force exerted by a muscle on the bone portion from a positional relationship of the bone portion that is continuous with the joint portion ;
A third calculation unit that calculates a first stress that acts on the joint based on the first dynamic model that shows the three-dimensional shape and the relationship characteristic, and the acting force;
A display control unit that displays a first stress image showing the first stress on a display unit;
Image analysis device equipped with.